Re: [PATCH] iio: accel: mma8452: Add single pulse/tap event detection

From: Jonathan Cameron
Date: Sun Nov 19 2017 - 09:47:20 EST

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On Wed, 8 Nov 2017 22:12:57 -0500
Harinath Nampally <harinath922@xxxxxxxxx> wrote:

> This patch adds following related changes:
> - defines pulse event related registers
> - enables and handles single pulse interrupt for fxls8471
> - handles IIO_EV_DIR_EITHER in read/write callbacks (because
> event direction for pulse is either rising or falling)
> - configures read/write event value for pulse latency register
> using IIO_EV_INFO_HYSTERESIS
> - adds multiple events like pulse and tranient event spec
> as elements of event_spec array named 'mma8452_accel_events'
>
> Except mma8653 chip all other chips like mma845x and
> fxls8471 have single tap detection feature.
> Tested thoroughly using iio_event_monitor application on
> imx6ul-evk board which has fxls8471.
>
> Signed-off-by: Harinath Nampally <harinath922@xxxxxxxxx>

The use of an either direction magnitude event is misleading.
Tap detection requires a timed sequence of events - a rapid
increase in acceleration followed by a rapid decrease.

I don't think we can fit tap detection into the existing
event types (which is annoying but there we are).

So.. I'd propose (and I want as much feedback on this as possible)

IIO_EV_TYPE_TAP

Then abuse iio_event_direction to specify single or double (the concept
of direction doesn't really apply to these in that sense so we'd always
have them set to none).

The alternative would be to full out for an abstract representation of
these events (like step detection) and define a channel type
IIO_TAP then detect a change in the number of taps (IIO_DIR_NONE), but
given we have directional taps we would need the modifier for that.
Hence no means of describing whether it is a single or double tap
short of burning channel taps. I'm also not sure we want to
remove the association with a particular sensor channel.

Hence I think I prefer option 1 but would like other's input on this...

Jonathan

> ---
> drivers/iio/accel/mma8452.c | 156 ++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 151 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 43c3a6b..36f1b56 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -72,6 +72,19 @@
> #define MMA8452_TRANSIENT_THS_MASK GENMASK(6, 0)
> #define MMA8452_TRANSIENT_COUNT 0x20
> #define MMA8452_TRANSIENT_CHAN_SHIFT 1
> +#define MMA8452_PULSE_CFG 0x21
> +#define MMA8452_PULSE_CFG_CHAN(chan) BIT(chan * 2)
> +#define MMA8452_PULSE_CFG_ELE BIT(6)
> +#define MMA8452_PULSE_SRC 0x22
> +#define MMA8452_PULSE_SRC_XPULSE BIT(4)
> +#define MMA8452_PULSE_SRC_YPULSE BIT(5)
> +#define MMA8452_PULSE_SRC_ZPULSE BIT(6)
> +#define MMA8452_PULSE_THS 0x23
> +#define MMA8452_PULSE_THS_MASK GENMASK(6, 0)
> +#define MMA8452_PULSE_COUNT 0x26
> +#define MMA8452_PULSE_CHAN_SHIFT 2
> +#define MMA8452_PULSE_LTCY 0x27
> +
> #define MMA8452_CTRL_REG1 0x2a
> #define MMA8452_CTRL_ACTIVE BIT(0)
> #define MMA8452_CTRL_DR_MASK GENMASK(5, 3)
> @@ -91,6 +104,7 @@
>
> #define MMA8452_INT_DRDY BIT(0)
> #define MMA8452_INT_FF_MT BIT(2)
> +#define MMA8452_INT_PULSE BIT(3)
> #define MMA8452_INT_TRANS BIT(5)
>
> #define MMA8451_DEVICE_ID 0x1a
> @@ -155,6 +169,16 @@ static const struct mma8452_event_regs trans_ev_regs = {
> .ev_count = MMA8452_TRANSIENT_COUNT,
> };
>
> +static const struct mma8452_event_regs pulse_ev_regs = {
> + .ev_cfg = MMA8452_PULSE_CFG,
> + .ev_cfg_ele = MMA8452_PULSE_CFG_ELE,
> + .ev_cfg_chan_shift = MMA8452_PULSE_CHAN_SHIFT,
> + .ev_src = MMA8452_PULSE_SRC,
> + .ev_ths = MMA8452_PULSE_THS,
> + .ev_ths_mask = MMA8452_PULSE_THS_MASK,
> + .ev_count = MMA8452_PULSE_COUNT,
> +};
> +
> /**
> * struct mma_chip_info - chip specific data
> * @chip_id: WHO_AM_I register's value
> @@ -784,6 +808,14 @@ static int mma8452_get_event_regs(struct mma8452_data *data,
> case IIO_EV_DIR_FALLING:
> *ev_reg = &ff_mt_ev_regs;
> return 0;
> + case IIO_EV_DIR_EITHER:
> + if (!(data->chip_info->all_events
> + & MMA8452_INT_PULSE) ||
> + !(data->chip_info->enabled_events
> + & MMA8452_INT_PULSE))
> + return -EINVAL;
> + *ev_reg = &pulse_ev_regs;
> + return 0;
> default:
> return -EINVAL;
> }
> @@ -848,6 +880,25 @@ static int mma8452_read_event_value(struct iio_dev *indio_dev,
> return ret;
> }
>
> + case IIO_EV_INFO_HYSTERESIS:
> + if (!(data->chip_info->all_events & MMA8452_INT_PULSE) ||
> + !(data->chip_info->enabled_events & MMA8452_INT_PULSE))
> + return -EINVAL;
> +
> + ret = i2c_smbus_read_byte_data(data->client,
> + MMA8452_PULSE_LTCY);
> + if (ret < 0)
> + return ret;
> +
> + power_mode = mma8452_get_power_mode(data);
> + if (power_mode < 0)
> + return power_mode;
> +
> + us = ret * mma8452_time_step_us[power_mode][
> + mma8452_get_odr_index(data)];
> + *val = us / USEC_PER_SEC;
> + *val2 = us % USEC_PER_SEC;
> +
> return IIO_VAL_INT_PLUS_MICRO;
>
> default:
> @@ -908,6 +959,24 @@ static int mma8452_write_event_value(struct iio_dev *indio_dev,
>
> return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, reg);
>
> + case IIO_EV_INFO_HYSTERESIS:
> + if (!(data->chip_info->all_events & MMA8452_INT_PULSE) ||
> + !(data->chip_info->enabled_events & MMA8452_INT_PULSE))
> + return -EINVAL;
> +
> + ret = mma8452_get_power_mode(data);
> + if (ret < 0)
> + return ret;
> +
> + steps = (val * USEC_PER_SEC + val2) /
> + mma8452_time_step_us[ret][
> + mma8452_get_odr_index(data)];
> +
> + if (steps < 0 || steps > 0xff)
> + return -EINVAL;
> +
> + return mma8452_change_config(data, MMA8452_PULSE_LTCY, steps);
> +
> default:
> return -EINVAL;
> }
> @@ -937,6 +1006,14 @@ static int mma8452_read_event_config(struct iio_dev *indio_dev,
>
> return !!(ret & BIT(chan->scan_index +
> ev_regs->ev_cfg_chan_shift));
> + case IIO_EV_DIR_EITHER:
> + ret = i2c_smbus_read_byte_data(data->client,
> + ev_regs->ev_cfg);
> + if (ret < 0)
> + return ret;
> +
> + return !!(ret & BIT(chan->scan_index *
> + ev_regs->ev_cfg_chan_shift));
> default:
> return -EINVAL;
> }
> @@ -988,6 +1065,25 @@ static int mma8452_write_event_config(struct iio_dev *indio_dev,
> val |= ev_regs->ev_cfg_ele;
>
> return mma8452_change_config(data, ev_regs->ev_cfg, val);
> +
> + case IIO_EV_DIR_EITHER:
> + val = i2c_smbus_read_byte_data(data->client, ev_regs->ev_cfg);
> + if (val < 0)
> + return val;
> +
> + if (state) {
> + val &= ~BIT(chan->scan_index *
> + ev_regs->ev_cfg_chan_shift);
> + val |= BIT(chan->scan_index *
> + ev_regs->ev_cfg_chan_shift);
> + } else {
> + val &= ~BIT(chan->scan_index *
> + ev_regs->ev_cfg_chan_shift);
> + }
> +
> + val |= ev_regs->ev_cfg_ele;
> +
> + return mma8452_change_config(data, ev_regs->ev_cfg, val);
> default:
> return -EINVAL;
> }
> @@ -1025,6 +1121,38 @@ static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
> ts);
> }
>
> +static void mma8452_pulse_interrupt(struct iio_dev *indio_dev)
> +{
> + struct mma8452_data *data = iio_priv(indio_dev);
> + s64 ts = iio_get_time_ns(indio_dev);
> + int src;
> +
> + src = i2c_smbus_read_byte_data(data->client, MMA8452_PULSE_SRC);
> + if (src < 0)
> + return;
> +
> + if (src & MMA8452_PULSE_SRC_XPULSE)
> + iio_push_event(indio_dev,
> + IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
> + IIO_EV_TYPE_MAG,
> + IIO_EV_DIR_EITHER),
> + ts);
> +
> + if (src & MMA8452_PULSE_SRC_YPULSE)
> + iio_push_event(indio_dev,
> + IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Y,
> + IIO_EV_TYPE_MAG,
> + IIO_EV_DIR_EITHER),
> + ts);
> +
> + if (src & MMA8452_PULSE_SRC_ZPULSE)
> + iio_push_event(indio_dev,
> + IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Z,
> + IIO_EV_TYPE_MAG,
> + IIO_EV_DIR_EITHER),
> + ts);
> +}
> +
> static irqreturn_t mma8452_interrupt(int irq, void *p)
> {
> struct iio_dev *indio_dev = p;
> @@ -1063,6 +1191,11 @@ static irqreturn_t mma8452_interrupt(int irq, void *p)
> ret = IRQ_HANDLED;
> }
>
> + if (src & MMA8452_INT_PULSE) {
> + mma8452_pulse_interrupt(indio_dev);
> + ret = IRQ_HANDLED;
> + }
> +
> return ret;
> }
>
> @@ -1130,8 +1263,10 @@ static const struct iio_event_spec mma8652_freefall_event[] = {
> },
> };
>
> -static const struct iio_event_spec mma8452_transient_event[] = {
> +
> +static const struct iio_event_spec mma8452_accel_events[] = {
> {
> + //trasient event
> .type = IIO_EV_TYPE_MAG,
> .dir = IIO_EV_DIR_RISING,
> .mask_separate = BIT(IIO_EV_INFO_ENABLE),
> @@ -1139,6 +1274,15 @@ static const struct iio_event_spec mma8452_transient_event[] = {
> BIT(IIO_EV_INFO_PERIOD) |
> BIT(IIO_EV_INFO_HIGH_PASS_FILTER_3DB)
> },
> + {
> + //pulse event
> + .type = IIO_EV_TYPE_MAG,
> + .dir = IIO_EV_DIR_EITHER,
> + .mask_separate = BIT(IIO_EV_INFO_ENABLE),
> + .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> + BIT(IIO_EV_INFO_PERIOD) |
> + BIT(IIO_EV_INFO_HYSTERESIS)
> + },
> };
>
> static const struct iio_event_spec mma8452_motion_event[] = {
> @@ -1202,8 +1346,8 @@ static struct attribute_group mma8452_event_attribute_group = {
> .shift = 16 - (bits), \
> .endianness = IIO_BE, \
> }, \
> - .event_spec = mma8452_transient_event, \
> - .num_event_specs = ARRAY_SIZE(mma8452_transient_event), \
> + .event_spec = mma8452_accel_events, \
> + .num_event_specs = ARRAY_SIZE(mma8452_accel_events), \
> }
>
> #define MMA8652_CHANNEL(axis, idx, bits) { \
> @@ -1368,9 +1512,11 @@ static const struct mma_chip_info mma_chip_info_table[] = {
> */
> .all_events = MMA8452_INT_DRDY |
> MMA8452_INT_TRANS |
> - MMA8452_INT_FF_MT,
> + MMA8452_INT_FF_MT |
> + MMA8452_INT_PULSE,
> .enabled_events = MMA8452_INT_TRANS |
> - MMA8452_INT_FF_MT,
> + MMA8452_INT_FF_MT |
> + MMA8452_INT_PULSE,
> },
> };
>

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Next in thread: harinath Nampally: "Re: [PATCH] iio: accel: mma8452: Add single pulse/tap event detection"
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